1. Field of the Invention
This invention is related to the addition of hydrogen and carbon monoxide to olefin compounds to obtain hydroxy-substituted cyclic compounds in the presence of a rhodium-containing catalyst and is more particularly related to such an addition conducted in the presence of a bi-solvent system.
2. Description of Related Processes in the Field
The compound 2-hydroxytetrahydrofuran is an important intermediate for producing 1,4-butanediol. A number of methods have been discovered for hydroformylating various unsaturated compounds to useful products.
U.S. Pat. No. 4,209,467 assigned to Daicel, Ltd. teaches a low pressure hydroformylation process in which the catalyst is a reaction product of a cobalt carbonyl compound with a nitrogen-containing heterocyclic compound having an enolic hydroxyl group on the carbon atom adjacent to the ring-forming nitrogen atom, such as 2-hydroxypyridine. Ordinarily, the pressures employed therein are in the neighborhood of 10 to 100 atmospheres. Unsaturated compounds taught as suitable for this hydroformylation process include ethylenically unsaturated hydrocarbons such as ethylene, propylene, butadiene, etc. and compounds such as allyl alcohol, allyl acetate, etc.
Closer to the invention disclosed herein are methods which involve rhodium catalysts. U.S. Pat. No. 3,980,670 discloses a process for manufacturing methacrylic acid and butyrolactone by hydroformylation of allyl esters of lower carboxylic acids in the presence of rhodium carbonyl complex catalysts followed by oxidation of the resulting formyl compounds with molecular oxygen to produce 4-acetoxy-n-butyric acid and 3-acetoxy-isobutyric acid as the major products. See also German Offen. No. 2,106,243 to BASF. Unsaturated compounds such as propylene may be hydroformylated by means of rhodium/triphenylphosphine/carbonyl complexes formed in situ using a special pre-forming step described in U.S. Pat. No. 4,400,549.
Even more on point are the following patents. U.S. Pat. Nos. 4,064,145 and 4,083,882 describe a method for producing tetrahydrofuran and 1,4-butanediol by reacting synthesis gas with allyl alcohol under hydroformylation conditions in the presence of a rhodium carbonyl-phosphine catalyst complex and various inert solvents such as organic aromatics, aliphatic hydroxylic organic solvents, etc. In both patents, the allyl alcohol conversion was reported to be 99% and 4-hydroxybutanal was typically obtained in 87 wt. % yield. The major by-product was 2-methyl-3-hydroxypropanal (12 wt. %). A rhodium catalyst complexed with special bisphosphine monooxide ligands is taught as catalyzing the hydroformulation of olefinic compounds in the presence of dimethylformamide solvent according to U.S. Pat. No. 4,400,548. Again, two phase solvent systems are not disclosed.
In J. Org. Chem., Vol. 45 (1980), 2132, C. U. Pittman, Jr. disclosed the hydroformylation of allyl alcohol to 4-hydroxybutanal and 3-hydroxy-2-methylpropanal using HRh(CO)(PPh.sub.3).sub.3 and its polymer-bound analogues. The selectivity of normal/branched products was studied as the function of reaction parameters and ligands employed. The highest normal/branched selectivities were reported with 1,1'-bis(diphenylphosphino)ferrocene at 80%. Benzene and o-xylene solvents were generally used.
In J. of Mol. Cat., Vol. 11 (1981), 233-246, N. A. deMunck reported a heterogeneous gas phase hydroformylation of allyl alcohol using a supported HRh(CO)(PPH.sub.3).sub.3 catalyst. A very high selectivity to 4-hydroxybutyraldehyde (97%) was achieved. However, the process is limited to only about 20% allyl alcohol conversion.
Kuraray disclosed the hydroformylation of allyl alcohol using rhodium catalyst in organic solvent such as benzene and toluene and a diphosphinoalkane. The overall n-/iso-ratio of the products were 86.6/13.4, (Kuraray, Japan. Pat. Open. No. 29412/1976, and No. 106407/1979 and Chemical Economy of Engineering Review, Vol. 12, No. 9, 1980). In additional patents (Kuraray, Japan. Pat. Open, No. 84508/1979 and British Pat. No. 1,493,154, 1977) to Kuraray, a modified Raney catalyst was claimed for the hydrogenation of hydroxybutyraldehydes into 1,4-butanediol and 3-methyl-1,3-butanediol.
Many of the systems described above lack good conversions of the unsaturated reactant compound and/or good selectivity to the desired product. Further, recovery of expensive rhodium catalysts is a problem in many of these processes. It would be an advance in the art if a method could be devised for hydroformulating compounds such as allyl alcohol while simultaneously solving the conversion, selectivity and catalyst recovery problems noted above.